The present invention relates generally, to the field of processing film units and, more particularly, to the processing of film units by immersing them in a processing fluid reservoir.
Systems of many kinds have been proposed for processing film units. One approach involves immersing an exposed film unit in a bath of processing liquid for initiating development thereof. In such an immersion system, a film unit enters a supply tank containing processing liquid. After being submerged in the liquid, the film unit is withdrawn from the container. Commonly assigned U.S. Pat. Nos. 3,405,619, 3,405,618; and 3,565,519 disclose examples of self-developing cameras having an immersion type processing apparatus therein. Another type of immersion system is of the so-called stand-alone type. Generally, these are for use in photographic darkrooms where the exposed film unit may be safely removed from the camera. Examples of such immersion type film processes are described generally in commonly assigned U.S. Pat. No. 3,288,609 and U.S. Pat. Nos. 3,943,539 and 4,361,392. In the foregoing systems, cooperating pairs of pressure-applying rollers are often actuated to transport the film units into or out of the processing fluid container. However, these rollers do not serve to seal the fluid within the container.
There are, however, problems associated with immersion type processing systems, especially those housing processing fluid usable in developing instant film. One is the criticality of keeping the fluid free from contaminants and others are to prevent the fluid from oxidizing or having its chemical activity diminished as a result of contact from the surrounding atmosphere. Still another is to prevent leakage of the processing liquid from its reservoir recepticle. Obviously, oxidation, contamination and loss of chemical activity diminishes the effectiveness of the processing fluid for the purposes intended.
With the exception of U.S. Pat. No. 4,361,392 the foregoing noted immersion systems employ a vertically standing container in which the film units enter and are withdrawn from the same opening. This factor limits, of course, the throughput of the systems inasmuch as successive units cannot be immersed until after the completion of the imbibition time of preceding unit.